Multi-element RFID coupler

ABSTRACT

An RFID communication system comprising a near field coupler that is capable of selectively communicating with a targeted transponder positioned among a group of multiple adjacent transponders. The coupler is configured to receive communication signals from a transceiver and transmit the signals to a targeted transponder in a transponder operating region. The coupler includes a number of radiating elements spaced apart and a switching element. The switching element selectively couples one or more of the radiating elements to the transceiver. The coupled elements transmit the signals into the transponder operating region by emanating a near field effect. The pattern of the near field effect may be adjusted by changing the combination of the coupled radiating elements.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to RFID couplers and, in particular, toUHF spatially selective couplers capable of selectively communicatingwith a targeted transponder from among of group of multiple adjacenttransponders.

2. Description of Related Art

Radio frequency identification (RFID) transponders, either active orpassive, are typically used with an RFID transceiver or similar deviceto communicate information from the transponders. In order tocommunicate, the transceiver exposes the transponder to a radiofrequency (RF) electromagnetic field or signal. In the case of a passivetransponder, the RF electromagnetic field energizes the transponder andthereby prompts the transponder to respond to the transceiver bymodulating the field in a well-known technique called backscattering. Inthe case of an active transponder, the transponder may respond to theelectromagnetic field by transmitting an independently powered replysignal to the transceiver.

Problems can occur when interrogating multiple adjacent transpondersregardless on whether the transponders are passively or activelypowered. For example, an interrogating electromagnetic signal mayactivate more than one transponder at a given time. This simultaneousactivation of multiple transponders may lead to communication, i.e. readand write, errors because each of the multiple transponders may transmitreply signals to the transceiver at the same time.

Several anti-collision management techniques commercially exist forallowing near simultaneous communication between multiple transpondersand a single transceiver while reducing communication errors. However,such anti-collision management techniques tend to increase systemcomplexity, cost, and delay response. Furthermore, such techniques areoften “blind” in that they cannot locate a given transponder or morespecifically recognize the position of a transponder within theinterrogating RF electromagnetic field. For example, in aprinter-encoder device, the device would not know whether thetransceiver was communicating with the transponder proximate to theprinthead or not.

Another method of preventing multiple transponder activation is toelectrically isolate transponders from one another. For example, devicesor systems may employ an RF-shielded housing or anechoic chamber forshielding the adjacent transponders from the electromagnetic field. Invarious applications, transponders individually pass though a shieldedhousing for individualized exposure to an interrogating RFelectromagnetic field. Unfortunately, RF-shielded housings add cost andcomplexity to a system. Furthermore, many devices are limited withregard to space or weight and, thus, cannot accommodate such shieldedhousings.

The challenge of avoiding multiple transponder activation may beespecially acute in some applications. RF printer-encoders are oneexample. RF printer-encoders are devices capable of programming andprinting a series or stream of transponders. The close proximity of thetransponders, during processing, and the space, cost, and weightrestrictions associated with such devices make multiple transponderactivation problematic. Furthermore, the space, cost, and weightrestrictions, among other factors, make anti-collision managementtechniques or shielding components for alleviating multiple transponderactivation less than desirable.

In light of the foregoing it would be desirable to provide a RF systemor device capable of interrogating individual transponders positionedamong multiple adjacent transponders without the need for anti-collisionmanagement techniques or shielding components. Furthermore, it would bepreferable to provide an RF communication system that adjusts todifferent transponder configurations and placements without increasingthe broadcast range of the RF transceiver signal.

BRIEF SUMMARY OF THE INVENTION

The present invention addresses the above needs by providing a nearfield coupler system adapted to provide selective communication betweena transceiver and a targeted transponder disposed among multipleadjacent transponders. The system includes a transceiver, a near fieldcoupler, and a transponder conveyance system. The transceiver is adaptedto transmit communication signals. The near field coupler is structuredto receive the communication signals from the transceiver and furtheradapted to broadcast electromagnetic signals into a transponderoperating region. The transponder conveyance system is adapted toposition at least one transponder within the transponder operatingregion. The near field coupler system may further include a printheadconfigured to print indicia upon the at least one transponder and acontroller for regulating the near field coupler based on the locationof the targeted transponder in the transponder operating region.

According to one embodiment, the near field coupler includes adielectric substrate, a terminating resistor, a ground plane, more thanone radiating element, and a switching element. The dielectric substratehas a first surface, a second surface, a first end and a second end. Theterminating resistor is disposed onto the dielectric substrate adjacentthe second end. The ground plane is adjacent to the second surface ofthe dielectric substrate. The radiating elements extend proximately fromthe first end to the second end of the dielectric substrate along thefirst surface, wherein the radiating elements are connected to theground plane through the terminating resistor. The switching element iselectrically connected to the radiating elements adjacent to the firstend of the dielectric substrate and is in electrical communication withthe transceiver. Also, the switching element is adapted to selectivelyactivate one or more radiating elements among the plurality of radiatingelements.

The switching element may include a number of switches, including havingthe same number of switches or less than the number of radiatingelements. At least one of the switches may be a PIN diode.

According to one embodiment, the near field coupler has three radiatingelements, wherein each element is a conductive strip disposed on thefirst surface of the dielectric substrate. The spatial relationshipbetween the strips may vary. For example, they may be substantiallyparallel to each other. The conductive strips may also be in a zig-zagconfiguration.

The near field coupler includes a terminating resistor, a dielectricsubstrate having a first side and second side, a ground plane adjacentto the first side of the dielectric substrate, a plurality of spacedradiating elements extending from a first end and a second end along thesecond side of the dielectric substrate. Each second end is connected tothe ground plane through the terminating resistor. A switching elementextends from the transceiver to the first end of each radiating element.The switching element is also configured to selectively couple at leastone of the radiating elements to the transceiver based on the locationof the targeted transponder to the coupler.

The switching element may include a plurality of switches. For example,the number of switches may be equal to or less than the number ofradiating elements. Furthermore, each switch may include a PIN diode.According to one embodiment, the near field coupler includes threeradiating elements that are substantially parallel to each other. Theradiating elements may also be in a zig-zag configuration.

Another aspect of the invention is a method of tuning the near fieldcoupler system. The method includes transmitting a communication signalfrom the transceiver to a near field coupler, wherein the switchingelement is adapted to provide selective electrical communication betweenthe transceiver and one or more radiating elements among the pluralityof radiating elements to define multiple switched radiating sets. Atransponder arranged in an unknown orientation is positioned within thetransponder operation region. An electromagnetic signal is broadcastedinto the transponder operating region based upon the selectivecommunication facilitated by the switching element between thetransceiver and the plurality of radiating elements. A power level foreach of the multiple switched radiating sets that accommodates areliable encoding process between the transceiver and the transponder isdetermined. The lowest power level among the power levels for each ofthe multiple switched radiating sets is determined for purposes offixing a preferred radiating set for interrogating subsequenttransponders arranged in the unknown orientation. The method may alsoinclude storing the preferred radiating set for subsequent transpondersarranged in the unknown orientation.

In yet another aspect of the present invention is a method ofcommunicating with the targeted transponder. The method includesadvancing the targeted transponder along a path, generating acommunication signal to the near field coupler, emanating a near fieldeffect in the proximity of the targeted transponder in order tocommunicate with the targeted transponder, and following the advancingtargeted transponder with the near field effect by changing thecombination of coupled radiating elements.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Having thus described the present invention in general terms, referencewill now be made to the accompanying drawings, which are not necessarilydrawn to scale, and wherein:

FIG. 1 is a side schematic view of a printer-encoder according to anembodiment of the present invention;

FIG. 2 is a simplified cut-away side view of a near field coupler systemhaving a coupler comprising a plurality of radiating elements structuredaccording to one embodiment of the present invention for creating a nearfield effect pattern that is transmitted in to a schematicallyillustrated transponder operating region;

FIG. 3 is a schematic illustration of a coupler interrogatingtransponders disposed on a carrier substrate in accordance with oneembodiment of the present invention;

FIG. 4 is a top view of a near field coupler according to one embodimentof the present invention; and

FIG. 5 is a top view of a near field coupler according to anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which some, but not allembodiments of the invention are shown. Indeed, this invention may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements. Like numbers refer to like elements throughout.

The present invention concerns an apparatus and method for enabling anRFID transceiver (sometimes referred to as an “interrogator”) toselectively communicate with a targeted transponder that is commingledamong or positioned in proximity to multiple adjacent transponders. Aswill be apparent to one of ordinary skill in the art, variousembodiments of the present invention are described below thatselectively communicate with a targeted transponder without requiringphysical isolation of the transponder using space-consuming shieldedhousings, anechoic chambers, or relatively more complex or costlyanti-collision management techniques. Furthermore, the inventiveconcepts described herein enable RFID transceivers to adapt to differingtransponder configurations, placements, or orientation within a selectedtransponder operating region.

Several embodiments of the present invention may be useful for reading,writing, or otherwise encoding passive transponders located on assemblylines, in inventory management centers where on-demand RFID labeling maybe needed, or in other similar circumstances. In various embodiments,one or more transponders are mounted to or embedded within a label,ticket, card, or other media form that may be carried on a liner orcarrier. In alternate linerless embodiments, a liner or carrier may notbe needed. Such RFID enabled labels, tickets, tags, and other mediaforms are referred to collectively herein as “media units.” As will beapparent to one of ordinary skill in the art, it may be desirable toprint indicia such as text, numbers, barcodes, graphics, etc., to suchmedia units before, after, or during communications with theircorresponding transponders.

The present invention has been depicted, for illustration purposes, inthe context of a specific application, namely, RFID enabled printersystems, also referred to herein as “printer-encoders.” Examples ofprinter-encoders are disclosed in commonly-owned U.S. Pat. Nos.6,481,907 and 6,848,616, which are hereby incorporated herein byreference. However, the inventive concepts described herein are notlimited to printer-encoders and may be applied to other RFID enabledsystems that may benefit from the ability to selectively communicatewith a targeted transponder disposed among multiple adjacenttransponders.

FIG. 1 illustrates an RFID printer-encoder 20 structured for printingand programming a series or stream of media units 24 according to oneembodiment of the present invention. In various embodiments, as shown inFIGS. 2 and 3, at least a few of the media units 24 include transponders26. As noted above, media units may include labels, cards, etc, that arecarried by a substrate liner or web 22 as shown.

Referring back to FIG. 1, the printer-encoder 20 includes severalcomponents, such as a printhead 28, a platen roller 29, a feed path 30,a peeler bar 32, a media exit path 34, rollers 36, a carrier exit path38, a take-up spool 40, a ribbon supply roll 41, a transceiver 42, acontroller 45, and a near field coupler 50. The web 22 is directed alongthe feed path 30 and between the printhead 28 and the platen roller 29for printing indicia onto the media units 24. The ribbon supply roll 41provides a thermal ribbon (not shown for clarity) that extends along apath such that a portion of the ribbon is positioned between theprinthead 28 and the media units 24. The printhead 28 heats up andpresses a portion of the ribbon onto the media units 24 to printindicia. The take-up spool 40 is configured to receive and spool theused ribbon. This printing technique is commonly referred to as athermal transfer printing. However, several other printing techniquesmay be used including, but not limited to, direct thermal printing,inkjet printing, dot matrix printing, and electro-photographic printing.

After printing, as shown in FIG. 1, the media unit web 22 proceeds tothe media exit path 34 where the media units are typically individuallyremoved from the web 22. For example, in one embodiment, pre-cut mediaunits 24 may be simply peeled from the web 22 using the peeler bar 32 asshown. In other embodiments, a group of multiple media units may bepeeled together and transmitted downstream to an in-line cutter forsubsequent separation (not shown). Various other known media unitremoval techniques may be used as will be apparent to one of ordinaryskill in the art.

In applications, such as the depicted embodiment, in which the mediaunits 24 are supported by a web 22, the web 22 may be guided out of theprinter-encoder 20 along the carrier exit path 38 by rollers 36 or otherdevices. Techniques and structures for conveying or guiding the web ofmedia units along the entire feed path of the printer-encoder are wellknown in the art and, thus, such techniques and conveyance systems arenot described in great detail.

The transceiver 42 is configured for generating and transmitting RFcommunication signals that are broadcasted by the spatially selectivemicrostrip near field coupler 50 located proximate the media feed path30. For purposes of the present specification and appended claims, thetransceiver 42 and the near field coupler 50 will be referred tocollectively as forming at least part of a communication system. As willbe explained in more detail below, the communication system transmits anear field electromagnetic signal or pattern in proximity to atransponder operating region. The communication system is configured toestablish, at predetermined transceiver power levels, a mutual couplingbetween the transceiver and a targeted transponder of a media unit thatis located in the transponder operating region. More specifically, asbest illustrated in FIGS. 2 and 3, as the media web 22 proceeds alongthe media feed path 30 through the transponder operating region C, datamay be read from and written to transponders 26 disposed on media units24 carried by the web 22.

In general, the transceiver is a device configured to generate, process,and receive electrical communication signals. One in the art wouldappreciate that similar devices such as transmitters, receivers, ortransmitter-receivers may be used within this invention. “Transceiver”as used in the present application and the appended claims refers to thedevices noted above and to any device capable of generating, processing,or receiving electrical and/or electromagnetic signals.

FIGS. 4 and 5 illustrate the near field coupler 50 in accordance withone embodiment of the present invention. The coupler 50 is structured inelectrical communication with the transceiver (not shown in FIGS. 4 or5) for receiving and broadcasting the signals originating from thetransceiver to the targeted transponder. In the depicted embodiment, thenear field coupler 50 includes a dielectric substrate 52, a terminatingresistor 58, a ground plane 60, an array of radiating elements 62, and aswitching element 68.

The dielectric substrate 52 has a first surface 53 and a second surface54 (visible only in FIG. 2) opposite the first surface 53. Each surfaceextends from a first end 55 and a second end 56. However, the generalshape of the dielectric substrate 52 may vary between applications. Forexample the dielectric substrate 52 may be a portion of a relativelylarger printed circuit board. The dielectric substrate 52 may be made orconstructed from various materials, including but not limited to, awoven glass reinforced epoxy laminate commonly referred to as “FR4” orflame resistant 4.

The array of radiating elements includes two or more radiating elements62, wherein each radiating element 62 is structured to convert theelectrical signals produced by the transceiver into an electromagneticfield. In the depicted embodiments, each radiating element 62 iscomprised of a conductive strip or line disposed on the first surface 53of the dielectric substrate 56. Each radiating element 62 generallyextends from the first end 55 to the second end 56 of the dielectricsubstrate 52. More specifically, according to the embodiment depicted inFIG. 4, the array includes three radiating elements 62 that aregenerally linear and parallel to each other. Also, the radiatingelements 62 may include non-linear portions. For purposes of the presentspecification and appended claims the term “non-linear portion” refersto a segment of a conductive line or strip having one or more turns orchanges in direction. A non-linear portion may have sharply definedturns to appear as a zig-zag type structure or may have relativelysmooth turns to appear as a wavy structure. Exemplary non-linearportions of the radiating elements 62 are depicted in FIG. 5. The mannerof which the radiating elements 62 are deposed on the first surface 53may vary. For example, the radiating elements may be etched, printed, ordeposited onto the first surface.

The terminating resistor 58 is proximate to one end of the array ofradiating elements 62 and disposed on the dielectric substrate 52. Theterminating resistor 58 is connected to each radiating element 62 andthe ground plane 60. The ground plane 60 is adjacent to the second andopposite surface of the dielectric substrate 52 as the radiatingelements 62.

On the opposite end of the radiating elements 62 from the terminatingresistor 58 is the switching element 68. The switching element 68 isconfigured to selectively couple and, thus, activate one or more of theradiating elements 62. As explained in further detail below, the term“activated” or “active” as used herein refers to a radiating elementelectrically connected to the transceiver such that the radiatingelement receives the signals from the transceiver and broadcasts thesignals along with any other active radiating element.

In various embodiments of the present invention, the switching element68 of the coupler 50 comprises a series of switches 70. The switchingelement 68, also, includes a main transmission line 72 extending from aninput end 73 to a branch end 74. The input end 73 is connected to thetransceiver. Extending between each radiating element 62 and the branchend 74 is a switch 74. The coupler 50 has three radiating elements 62and one switch 64 per radiating element 62 therefor, allowing for anycombination of the radiating elements 62 to be coupled or decoupled tothe transceiver at one time. However, one in the art will appreciatethat the number of radiating elements 62 and the number of switches 70per element 62 may vary between embodiments. For example, the number ofswitches 70 may be less than the number of radiating elements 62. One inthe art will appreciate the different types of switches 70 that may beused within this invention, including, but not limited to, PIN diodes.

Notably, the near field coupler 50 of the present invention, and asshown in FIGS. 4 and 5, operates as one or more one-half wavelengthunmatched transmission lines, rather than operating as a standing waveradiating antenna or magnetic field generating coil. More specifically,each radiating element 62 operates as a transmission line when coupledto the transceiver, i.e. activated, by the switching element 68. Invarious embodiments of the present invention, each transmission line mayor may not be “matched,” i.e. the characteristic impedance of thetransmission line may differ from that of the terminating resistor 58.For example, in one embodiment, the characteristic impedance of thetransmission line may be 15 ohms and the characteristic impedance of theterminating resistor 58 may be 50 ohms. The signals generated by thetransceiver pass along the one or more active radiated elements 62 ofthe array to the terminating resistor 58. As illustrated best in FIG. 2,these signals generate a near field effect that emanates from the edgesof the one or more active radiating elements 62. The near field effectcouples with the targeted transponder 26 passing through the transponderoperating region C. For purposes of the present invention and appendedclaims the term “near field effect” refers to the one or more relativelylocalized electromagnetic fields 78 that are also commonly referred toas “leaky” electromagnetic fields, as further described in “Leaky Fieldson Microstrip” L. O. McMillian et al. Progress in ElectromagneticsResearch, PIER 17, 323-337, 1997 and in commonly owned U.S. PatentApplication Publication Nos. 2005/0045723 and 2005/0045724 to Tsirlineet al., which are hereby incorporated by reference in their entirety.The effective range of couplers relying on such leaky electromagneticfields 78 is limited because the fields degrade, at an exponential rate,with increasing distance from the coupler 50. This limited range reducesthe likelihood that a given transceiver's signal will activatetransponders outside the transponder operating region C.

As described above and as schematically illustrated in FIG. 2, eachactive radiating element is structured to broadcast a localizedelectromagnetic field 78 into the transponder operating region C. Forexample, as shown in FIG. 2, the three depicted radiating elements arecoupled and each broadcasts an electromagnetic field at a pointproximate to the corresponding radiating element 62. These points areillustrated in FIG. 2 by the lower case letters d, e, and f. One aspectof the present invention is selectively coupling and decoupling theradiating elements via the switching element to manipulate or adjust thenumber and location or pattern of the electromagnetic fields 78 enteringinto the transponder operating region C.

According to one embodiment of the present invention, the pattern of theelectromagnetic fields is adjusted to correspond to the placement ororientation of the targeted transponder within the transponder operatingregion. For example, as discussed above, within a printer-encoder, thetransponders 26 are embedded in the stream of individual media units 24,as shown in FIG. 3. However, the size and shape of the media units 24 orthe placement of the transponders 26 within the media units 24 may varydepending on the media unit configuration. Increasing the range of thenear field effect produced by the coupler 50 to account for suchvariations in the location or placement of the transponder 26 iscounterproductive to the objective of limiting the range to preventinadvertent activation of untargeted transponders 26. By altering thepattern of the near field effect, i.e. changing the locations and/ornumber of electromagnetic fields, the coupler 50 can accommodatedifferent locations or orientations of the transponders 26 withoutnecessarily increasing its range.

Also, the switching element may be configured to adjust the coupling anddecoupling of the radiating elements 62 to correspond to the moving ofthe transponder 26 through the transponder operating region C. In otherwords, the near field pattern is altered such that the near fieldpattern is approximately centered on the transponder 26 while thattransponder 26 is moving. For example, in FIG. 2, the coupler 50 mayhave only one active radiated element 62 at any given time.Specifically, as the transponder 26 enters the transponder operatingregion C, the radiating element 62 corresponding to the most upstreampoint, point f, is active, as the transponder 26 further proceeds thedecoupling and coupling of the radiating elements 62 follows thetransponder 26. Therefore, point f is deactivated by the decoupling ofthe corresponding radiating element 62, and point e is activated by itscorresponding radiating element 62 as the transponder 26 approachespoint e. Likewise, point e is deactivated and point d is activated byits corresponding radiating element 62 as the transponder 26 nears thedownstream area of the transponder operating region C.

Another aspect of the present invention is a method of tuning a nearfield coupler for a printer-encoder to a particular media unitconfiguration. The method includes loading the printer-encoder 20, asshown in FIG. 1, with a web 22 of media units 24 having embedded orattached transponders 26 and advancing at least one media unit 24 to thetransponder operating region C, as shown in FIG. 2. In order to properlytune the coupler to the loaded media unit's configuration, or morespecifically to the orientation of the transponder within thetransponder operating region, a tuning cycle is executed. As a samplemedia unit having a transponder is in the transponder operating region,the transceiver generates a test signal and transmits the signal throughthe coupler. The controller or similar device commands the switchingelement to execute a number of possible combinations of coupled anddecoupled radiating elements. In order to determine a “preferredradiating set” of coupled and decoupled radiating elements, eachcombination is monitored to determine what combinations of coupled anddecoupled radiating elements, referred to herein as “radiating sets,”allow for a reliable encoding process for the targeted transponder.Furthermore, the controller may regulate the power level of the signalto determine what combination provides a reliable encoding process atthe lowest power level. The combination that ensures a reliable encodingprocess at the lowest power level is determined to be the preferredradiating set for that particular media unit configuration. “Reliableencoding process” as used within this specification and the appendedclaims means the ability for the transceiver to effectively communicatewith the targeted transponder through the near field effect created bythe coupled radiating elements, while minimizing inadvertentcommunication with untargeted transponders.

Once the preferred radiating set is known, that radiating set is set forthat media unit configuration and the printer-encoder proceeds with thenormal processing and programming of the media units. The timing orfrequency of executing a tuning cycle may vary. For example, once thepreferred radiating set is known for a particular media unitconfiguration that preferred radiating set may be stored within theprinter-encoder. When that particular media unit configuration is used,an operator may be able to enter that configuration into theprinter-encoder through a keypad (not shown) allowing the controller toset the preferred combination without re-executing a tuning cycle. Also,the controller may be programmed to run a tuning cycle after a certainevent such as the turning on of the printer-encoder, the loading ofmedia units, the passage of certain amount of time, or afterpredetermined number of media units are processed.

The present invention provides a near field coupler having a limitedrange so as to minimize possible multiple activation of adjacenttransponders outside the transponder operating region. The switchingelement allows for the altering of the near field effect pattern toadjust for a number of media unit configurations without necessarilyincreasing the range of the coupler. The tuning cycle optimizes or tunesthe coupler's radiating elements to provide a reliable encoding processat a relatively low power level.

Many modifications and other embodiments of the invention set forthherein will come to mind to one skilled in the art to which thisinvention pertains having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the invention is not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation.

1. A near field coupler comprising: a dielectric substrate having a first surface, a second surface, a first end and a second end; a terminating resistor disposed on the dielectric substrate adjacent the second end; a ground plane adjacent to the second surface of the dielectric substrate, a plurality of radiating elements extending proximately from the first end to the second end of the dielectric substrate along the first surface, wherein each of the plurality of radiating elements has a length of one-half wavelength or integer multiple thereof and is connected to the ground plane through the terminating resistor such that each of the plurality of radiating elements and the ground plane together form a one-half wavelength or integer multiple thereof transmission line, the terminating resistor is selected such that the near field coupler operates as one or more unmatched transmission lines; and a switching element electrically connected to the plurality of radiating elements adjacent to the first end of the dielectric substrate, wherein the switching element is provided in electrical communication with the transceiver and configured to selectively deactivate one or more radiating elements among the plurality of radiating elements by decoupling from the one or more radiating elements such that a near field effect is produced by the near field coupler in an operating region, the near field effect moving within the operating region and following the advancement of a targeted transponder.
 2. The near field coupler according to claim 1, wherein the switching element is comprised of a plurality of switches and wherein the number of switches is equal to or less than the number of radiating elements.
 3. The near field coupler according to claim 2, wherein at least one of the plurality of switches is a PIN diode.
 4. The near field coupler according to claim 1, wherein the plurality of radiating elements includes three radiating elements and each radiating element is a conductive strip disposed on the first surface of the dielectric substrate.
 5. The near field coupler according to claim 1, wherein the plurality of radiating elements are parallel to each other.
 6. The near field coupler according to claim 1, wherein the plurality of radiating elements are in a zig-zag configuration.
 7. A near field coupler system adapted to provide selective communication between a transceiver and a targeted transponder disposed among multiple adjacent transponders, the near field coupler system comprising: a transceiver configured to transmit communication signals; a near field coupler structured to receive the communication signals from the transceiver and further configured to broadcast electromagnetic signals as a near field effect into at least a portion of a transponder operating region, the near field coupler comprising: a plurality of radiating elements, and a switching element electrically connected to the plurality of radiating elements and the transceiver, wherein the switching element is configured to selectively deactivate one or more of the radiating elements among the plurality of radiating elements, by decoupling from the one or more of the radiating elements, to adjust a pattern of the near field effect in the transponder operating region; a transponder conveyance configured to advance at least one transponder on a path through the transponder operating region; and a controller configured to control the near field coupler such that the pattern of the near field effect follows the advancement of the at least one transponder within the transponder operating region by operating the switching element based on at least one of an orientation and a location of the transponder within the transponder operating region.
 8. The near field coupler system according to claim 7, wherein the switching element is comprised of a plurality of switches and wherein the number of switches is equal to or less than the number of radiating elements.
 9. The near field coupler system according to claim 7, further comprising a printhead configured to print indicia upon the at least one transponder.
 10. The near field coupler system according to claim 7, wherein the near field coupler further includes a dielectric substrate and each of the radiating elements comprised of a conductive strip disposed on the dielectric substrate.
 11. The near field coupler system according to claim 10, wherein the conductive strips are parallel to each other.
 12. The near field coupler system according to claim 11, wherein the conductive strips are in a zig-zag configuration.
 13. A method of communicating with a targeted transponder, the method comprising: advancing the targeted transponder along a path; generating a communication signal to a near field coupler having a plurality of radiating elements and a switching element for selectively deactivating at least one of the radiating elements by decoupling from the at least one of the radiating elements; emanating, into at least a portion of a transponder operating region, a near field effect from a combination of activated radiating elements in the proximity of the targeted transponder in order to communicate with the targeted transponder; and following the advancement of the targeted transponder with the near field effect, the near field effect moving within the transponder operating region by changing the combination of activated radiating elements via operation of the switching element based on at least one of an orientation and a location of the targeted transponder within the transponder operating region.
 14. The method according to claim 13, wherein at least one of the combinations of activated radiating elements includes one activated radiating element. 